Denticulus
by Tsarina Torment
Summary: A seven-year-old body brings seven-year-old problems, including one Conan appears to have forgotten about. Seven-year-olds do not already have their adult teeth, not even shrunken teens turned seven-year-olds.


**Disclaimer: I don't own Detective Conan**

"Hey, Kudo!"

Kudo Shinichi, currently known as Edogawa Conan, suppressed a sigh of irritation. What the hell was Hattori doing in Beika? He was fairly certain he'd told the Osakan to give him warning before he descended on them for the weekend, or however long he was staying for this time.

"Shinichi nii-san?" Ayumi exclaimed, looking around excitedly for the aforementioned teenage detective. This time Conan couldn't quite suppress the groan that wanted to force its way past his lips.

"Hello, _Heiji-niisan_ ," he chirped, all smiles at the sight of his 'favourite niisan'. Well, all smiles except for his eyes, which were glaring daggers at the other detective, who at least had the grace to look sheepish.

"How ya guys doing?" he asked, squatting down in front of the five of them, Genta and Mitsuhiko also greeting him – Shinichi somehow hid his fury at being referred to as Hattori's apprentice yet again – while Haibara stood off to the side, frowning lightly. Like him, she didn't like Hattori's constant slip-ups.

"We're doing well, thank you," the ever-formal Mitsuhiko replied. "What brings you here?"

"Hey, hey, is it a case?" Genta interrupted, pushing past Conan and Mitsuhiko to stare directly at Hattori. "What is it? We'll help!" Hattori laughed.

"No, no," he admitted, waving his hand negatively. "Can't I just visit my favourite kid detectives?" Conan side-eyed him viciously even as the true children ahhed in disappointment before immediately perking up again.

"Come play football with us!" Genta demanded, and before Hattori could protest that baseball was the far superior sport (he was wrong on that but Conan wasn't going to start that argument) Ayumi grabbed his hand and all but dragged him with them to the park so they could play. At least he'd be able to show Hattori up in this, Conan thought smugly. A thorough beating at football was the most payback he could give in the current situation, and he was going to give it.

The teams were split into Conan and Ayumi against Hattori, Mitsuhiko and Genta. Haibara had passed with the air of a woman that knew exactly what was about to go down and would rather laugh from the sidelines than be involved, and the boys had shot down Hattori's suggestion that he would team with Conan immediately, citing that it wasn't fair if the best player also got the adult. Conan had joined in the protests, to Hattori's clear dismay. He couldn't beat the guy if they were on the same team, after all. He had to admit he was going to feel bad for thrashing Mitsuhiko and Genta, though. They hadn't done anything wrong.

The game started predictably. Hattori, for all the size advantage he had, couldn't stop Conan running rings around him – literal rings; this was payback after all – and with a triumphant grin the first goal was for the shrunken detective. Then things went wrong.

With the goal scored, possession automatically passed to Hattori, and he was intent on using his longer legs to stop Conan claiming the ball again. It didn't work, but as Conan snuck the ball from the other he found himself tripping over the edge of Hattori's shoe, and landed heavily on the ground.

The ball was immediately forgotten as the children ran over to him, Hattori already helping him back to his feet.

"Ya okay, K-Conan?" he asked, looking him up and down as he searched for injuries. Conan felt thoroughly humiliated. Hattori treated him like a kid sometimes, but that was always in jest. This time… it didn't feel like it.

"I'm fine," he said, then made a face. Something in his mouth had moved. Something that wasn't supposed to. He swirled his tongue around and found something solid that shouldn't be there, which he promptly spat out into his palm.

It was a tooth. To be precise, it was an upper incisor, his mind helpfully supplied as he froze. What… why had a tooth fallen out? He hadn't landed that hard; his jaw had barely touched the ground!

"I lost a tooth," he said dumbly, staring at the offending object in his hand. "That shouldn't happen. Why did I lose a tooth?"

"Lemme see," Hattori demanded, and Conan dutifully opened his mouth. "Hmm…" The dark skinned boy stared intently for a second or two before he fell back on his haunches in peels of laughter.

"Hat- Heiji-niisan this isn't funny!" Conan yelled, furious. What was that idiot doing? "A tooth! I lost a tooth!"

"Yer a kid," Hattori managed between barks of laughter. "'Course ya lost a tooth." The worried faces of the Detective Boys were replaced with a sudden understanding, as the horrid realisation dawned on Conan.

"It's perfectly natural," Mitsuhiko began to explain, one finger pointed upwards as he began his educational speech. "The first teeth to be lost are the front teeth, when we're 6 or 7. After that, we lose-"

Conan tuned out the lecture. Mitsuhiko seemed delighted to know something Conan didn't and as much as he wanted to snap that he knew all that, thank you very much, if he did that he was then going to have to explain why he freaked. How were you supposed to explain that you'd already lost your deciduous teeth once? He'd assumed that he'd still kept his adult teeth, but now that he thought about it, that had been naïve of him. If the rest of his body had reverted to his seven-year-old state, then why not his dentition?

He did not relish the idea of having to go through that again. As a teenager (albeit one in the body of a child), his psyche rebelled at the idea of losing teeth. Hopefully Haibara would come up with a cure before he lost too many deciduous teeth for the second time. The female herself was eyeing him with thinly veiled amusement. Not a welcome reaction, but expected.

Speaking of unwelcome reactions, Hattori was still laughing his head off very unhelpfully. Conan kicked him.

"Heiji-niisan," he whined, glaring at him viciously.

"S-sorry," the other teen gasped, clearly not interested in curbing his mirth. "Yer face!"

"What if it doesn't grow back?" he demanded, remembering at the last second to make it sound less like the true concern of 'I've already had my adult dentition erupt once, what if it isn't there anymore' and more like a slightly confused and nervous seven-year-old. Didn't really work, but at least he could say he tried.

That shut Hattori up as the full implication finally registered.

"I don't think you need to worry, Edogawa-kun." Finally Haibara had something to say, and it wasn't something along the lines of dragging him to be experimented on. That was a pleasant surprise. "It's rare for a child's deciduous tooth to fall out at our age if the permanent tooth isn't behind it." Common sense, but not really taking their situation into account. That hadn't been what Conan was aski-

"My permanent first upper left incisor has already erupted," she hissed in his ear, interrupting his thought process. "Stop panicking. You're drawing too much attention." Sure enough, a crowd of concerned adults seemed to be watching them, and Conan gritted his teeth – noticing the gap and hating it. He did not want to deal with concerned adults right now.

"S'okay!" Hattori called out to the observing adults suddenly, startling Conan. "The kid just had his first baby tooth fall out and it startled him a bit, is all!" Conan turned to hiss a complaint for drawing more attention to them when the adults tittered slightly, or smiled in understanding, and turned away. "Now let's get ya back to Neesan," the Osakan said to him, grinning. Conan did not like that grin. "Gotta throw that tooth on a roof so yer adult one grows in properly, after all!"

"You are enjoying this far too much," Conan hissed at him as he was dragged back in the direction of the Detective Agency by the kids.

It transpired that Haibara had been right, and that his permanent dentition was growing through as it should. That should have been the end of that, except the Detective Boys (and he suspected Hattori also had a hand in it but he couldn't find any proof, dammit), had spread the story of 'Conan's first tooth loss' to every adult they knew. Of course, this just had to include Ran (not disastrous; she just smiled kindly at him and reassured him that it was a normal reaction), and Sonoko (who was never going to let 'the brat' live it down. Ever).

It even spread to _KID_ , and Conan did not want to know how or why, but the next heist he went to the thief gave an eerily accurate mimic of his voice panicking about losing all his teeth. He was certain he hadn't been quite that hysterical – KID was just laying on the hyperbole in his usual fashion, right?

 **After the episode with Ayumi and the dentist, I started wondering about Conan's (mental) statement that at least he had all his adult teeth already, and decided he was probably unaware rather than that being fact. After all, the adult dentition is too large to fit in a seven year old's mouth. This might be a good time to point out I'm an osteology student so I have to know things about teeth, including that the incisors are first to go, and it happens at about Conan's age. Too good an opportunity to miss!**

 **Heiji's comment about throwing the tooth on the roof comes from Wikipedia telling me that's what they do with deciduous teeth in Japan (upper teeth onto roofs, lower teeth to the ground). If someone with better knowledge than me about Japanese customs wants to correct me, feel free!**

 **Thanks for reading!**

 **Tsari**


End file.
